Problem: $ \left(\dfrac{1}{81}\right)^{-\frac{1}{2}}$
Explanation: $= 81^{\frac{1}{2}}$ Figure out what goes in the blank: $\Big(? \Big)^{2}=81$ Figure out what goes in the blank: $\Big({9}\Big)^{2}=81$ So $\left(\dfrac{1}{81}\right)^{-\frac{1}{2}}=81^{\frac{1}{2}}=9$